The present invention relates to a new and improved construction of apparatus for the direct cooling of a strand, especially during the continuous casting of steel, and which apparatus is of the type embodying strand guide segments equipped with spray nozzles for the application of a cooling agent to the strand and devices for the infeed and adjustment of the quantity of such cooling agent.
According to a known apparatus for the cooling of a strand, fixed supports or holders in the form of nozzle blocks are located in the cooling zone, such nozzle blocks possessing a number of infeed lines or conduits for the cooling agent or coolant, typically water. The nozzles are connected in groups to the infeed lines, so that the cooling can be accommodated to the changing parameters, such as strand format or shape, quality of the steel, casting speed and so forth, by turning-on and turning-off selected groups of nozzles.
This state-of-the-art apparatus is quite expensive and complicated in its design owing to the prevailing piping or conduit arrangements. Shutting down of nozzles during the continuous casting operation is associated with the drawback of the clogging of the nozzle openings directed towards the hot strand, so that there occur irregularities in the cooling action. In order to avoid as far as possible such irregularities and disturbances there is required extensive maintenance work at the cooling zone, the accessibility to which is extremely difficult. If the accessibility is to be improved then it is necessary to dismantle the nozzle blocks, a job which is extremely time-consuming and results in longer downtimes of the installation. In order to be able to accommodate the cooling action to the changing parameters there is required in many instances a change in the pressure of the cooling agent. Since, upon changes in pressure, the spray angle and the spray characteristic of the individual nozzles only can be maintained constant within a small pressure change range, the actual cooling thus only corresponds to the prescribed values over a small range. In the case of continuous casting installations utilizing large changes in the strand format and strand speed the accommodation of the cooling of the strand to the changed conditions only can be realized with extremely great expenditure.
Upon changing the aforementioned parameters, the pressure changes and the therewith associated change in the quantity of water oftentimes is insufficient for accommodation to the cooling conditions. There are required nozzles with other rated water quantities. Such exchange and replacement of the nozzles is normally much too time-consuming with the prior art installations, so that there is only possible a limited change in the parameters.